Hydraulic jack.



No. 861,714. PATENTED JULY 30, 1907. H. G. DUDGEON.

HYDRAULIC JACK.

' APPLICATION FILED APR.26.1907.

2 sums-enm- 2.

FIG. 2

HENRY O. DUDGEON, OF LOOUST VALLEY, NEW YORK.

HYDRAULIC JACK.

Specification of Letters Patent.

Patented July 30, 1907.

Application filed April 26, 1907. Serial No. 370,363.

To all whom it may concern:

Be it known that I, HENRY G. Dr'meEoN, a citizen of the United States, and a resident of Locust Valley, Nassau county, Long Island, State of New York, have invented certain new and useful Improvements in Hydraulic Jacks, of which the following is a specification, reference being had to the accompanying drawings, in which Figure 1 illustrates a vertical sectional view of an hydraulic jack embodying the invention, some of the parts appearing in elevation; Fig. 2 illustrates an enlarged view of the headof the jack, showing the invention in position therein, some of the parts appearing in elevation. Fig. 3 illustrates. a modified construction.

In the drawings I illustrate the invention as applied to a common form of jack, that is to say, one in which the head of the ram is hollow and acts as the reservoir for the liquid, and-the pump in this instance is located in the ram and receives its supply of liquid from the reservoir by the liquid passing through the piston of the pump into the force chamber thereof. It will be understood that this is one form only of many in which the invention may be employed.

In hydraulic jacks it has heretofore been customary to supply air vents for the reservoir, so that as the liquid therein decreased by reason of the operation of the pump, or increased again, returning to normal amounts becauseof the back flow of the liquid consequent on lowering the ram, the vacuum, or air pressure, as the case might be, in the reservoir would be avoided. These air vents have been made in a variety of ways and many devices have been resorted to whereby the vents, while allowing the passage of air, would not permit the escape of the liquid, if the jack was left in a position other than substantially vertical, which is very apt to be the case. Letters Patent of the United States numbered 848,641 and dated April 2, 1907, were granted to me for such an improvement which I have found the most useful and efficient construction known to me, but during my investigations in connection therewith I havemade a discovery which an examination of prior devices for venting jacks, shows me has never beenknown before, whereby I am enabled to improve upon the invention patented to me as aforesaid.

My discovery is as follows: Heretofore it has always been supposed that it was necessary to provide means whereby air could pass into the reservoir to prevent the formation of a vacuum therein consequent upon the pumping of the liquid therefrom, as well as means to allow the escape of air from the reservoir to prevent air pressure arising therein consequent upon the return of the liquid to the reservoir on lowering the ram. Now the discovery I have made is that there is no necessity for any air inlet into the reservoir because the vacuum formed in the pump bore consequent on the upward or intake stroke of the piston, exceeds thq vacuum in the reservoir, or at least neutralizes such vacuum, so that, as the jack, when in operation, is always sufficiently vertical, the suction in the pump bore plus the action of gravity on the liquid will always assure suitable supply thereof to the pump. Consequently I am enabled to very greatly simplify the venting device by employing a single valve only, which is the one which opens outwardly from the reservoir, and because of this I can still further simplify the device, because I have so designed the parts that this single valve can be bodily removed from the plug in which it is set by simply unscrewing a little supplemental plug which is the Work of a moment only. It is necessary to exert some force on the pumping lever to create the requisite vacuum or suction in the pump chamber, but this is not appreciated, especially since the upstroke is effected so much easier than the down stroke. The reason an out going vent from the reservoir is required, although there is no apparent opening for the entrance of air thereto, is that it is practically impossible to create a con tinu ing vacuum in such a structure as the reservoir of a jack. The air will enter, little by little, through the joints of the parts, (which however are so small as to preclude the passage of the liquid through them) as the water slowly subsides during the pumping operaas short a time as possible)-consequently the prompt escape of the air from the reservoir at this part of the operation is necessary.

Referring now to the drawings, (Fig. l) A represents the body of the jack, B the ram, 0 the pump in the ram, D the piston, E the piston rod, F the knuckle, G the lowering device, G, the hollow head of the ram which constitutes the reservoir H.

Referring now more particularly to Fig. 2, I is a plug threaded intd the head of the ram as shown. J is a valve seated in the upper end of a passage K made in the plug. L is a spring which abuts at one end against the valve and at its other end against a little supplemental plug. M threaded into the main plug L. N is a blow hole made in the plug through which the air blows forcibly upon lowering the ram. This blow hole is made by drilling through the side of the plug just above the valve and then intersecting this hole with another drilled down from the top of the plug as shown; the outer end of the horizontal drilling may be soldered or plugged up in any suitable way, as indicated at O, or it may be left open, if preferred, as an aid in cleaning the blow hole should it get stopped up inany way. I

drill these two holes, the horizontal one and the vertical one, instead of making a single one inclinedupto any special construction.

wardly from the chamber above the valve, for the reason that it is very desirable to prevent the entrance of dirt through this blow hole, and if it was drilled so that dust and dirt entering its upper end would fall into the valve chamber, it would be apt to work into the valve seat and perhaps through the valve and into the liquid into the reservoir, so finding its way into the pump piston valve and thus make trouble; but when the holes are drilled as I show them, then if any dirt or dust should enter at the upper end of the vertical drilling it will drop to the bottom of the horizontal drilling andrest there until the lowering of the ram occurs and then the forcible blast of ejected air will blow it out again. 7

As above suggested, my invention may be embodied in a variety of forms. I therefore do not limit myself That illustrated in Figs. 1 and 2, however, is a desirable construction. As an illustration of another form, that shown in Fig. 3 may be employed, in which a is the valve, b a weight, shown in this case as a metallic ball, which in all positions of the jack is held by the inclined surfaces 0, c, relative to the lower surface of the valve, so that should the jack be tipped over the ball will, under the action of gravity,

seat the valve and hold it on its seat. The inclined surfaces 0, 0, may beneficially be made in a supplemen- Thus there is possibility of loss of liquid by evaporation.

I illustrate it merely to show another and differently organized form in which my invention may be con-- structed.

I claim: 1. An hydraulic jack having in combination a reservoir,

:1 pump which gets its supply of liquid from the reservoir, means to actuate the pump which extend from the outside of the reservoir to its inside, a valve opening outwardly from the reservoir, a blow hole and means to seat the valve the walls of said reservoir being otherwise imperforate.

2. An hydraulic jack having in combination a reservoir, :1 pump which gets its supply of liquid from the reservoir,

means to actuate the pump through the joints of which air.

ervoir heing' otherwise imperforate.

4. An hydraulic jack having in combination a reservoir. :1 pump which gets its supply of liquid from the reservoir, means to actuate the pump from the exterior of the jack, a plug set in the wall of the reservoir, a valve in the plug which opens outwardly from the reservoir, a blow hole in the plug having a substantially horizontal and a substan tially vertical passage and means to seat the valve the .walls of said reservoir being otherwise imperforate.

An hydraulic jack having in combination a reservoir. :1 pump which gets its supply of liquid from the reservoir, means to actuate the pump from the exterior of the jack, a plug set in the Wall of the reservoir, a valve in the plug which opens outwardly from the reservoir, a blow hole in the plug and means which normally resent the valve in all positions of the jack the walls of. said reservoir being otherwise imperforate. v

6. An hydraulic jack having in combination a reservoir :1 pump which gets its supply of liquid from the reservoir, means to actuate the pump from the exterior of the jack, a plug set in the wall of the reservoir, 8. spring actuated valve in the plug which opens outwardly from the reservoir and Z1 blow hole in'the plug the walls of said reservoir being otherwise imperforate.

In testimony whereof I have signed my .name to this specification in the presence of twosubscribing witnesses.

HENRY C. 'DUDGEON.

Witnesses:

SILAS D. WRIGHT, \PHEBE E. WRIGHT.

the plug and means to seat the valve the walls of said ms 1 

